Re: [Qemu-devel] [PATCH] trace: only create simple backend trace files when an event is emitted.

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Mon, Feb 08, 2016 at 10:51:55AM -0800, Hollis Blanchard wrote:
> Previously, trace record files (created by st_set_trace_file_enabled(true))
> were created by the simple backend at initialization time, even if no events
> were actually enabled.
> 
> As a consequence, the working directory would become littered with trace-PID
> files just by enabling the simple backend at configure time, even when no
> -trace options were used.
> 
> ---
> I've been using this to avoid creation of empty trace record files. I haven't
> done any scientific performance studies, but an extra function
> call/conditional/return when recording every trace event doesn't seem to have
> any noticeable effect.
> 
> Signed-off-by: Hollis Blanchard <hollis_blanchard@mentor.com>
> ---
>  trace/simple.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

By the way, thanks for the patch.  I didn't see it because my
maintainership scripts use my stefanha@redhat.com email account that is
listed in ./MAINTAINERS.

Stefan

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